1. Field of the Invention
This invention relates to the field of information networks, and more particularly relates to the management of resources in a router capable of routing information over a network.
2. Description of the Related Art
Today's networks carry vast amounts of information. High bandwidth applications supported by these networks include streaming video, streaming audio, and large aggregations of voice traffic. In the future, these bandwidth demands are certain to increase. To meet such demands, large communications systems have been built to provide the needed bandwidth. As a result, the equipment handling such traffic has become increasingly complex. Such systems commonly occupy multiple full-height telecommunications racks and contain a number of interdependent subsystems which must inter-operate seamlessly with one another. These systems may communicate with one another using one or more communications subsystems.
Moreover, the combination of voice and data communications has put new constraints on such systems. While both forms of service require maximum up-time, failures in the voice communications arena are particularly sensitive to failures that impact end users. In packet switched networks, failures are merely routed around and lost data resent. Unless the data is used in a time- or data-critical application (e.g., on-line banking, virtual private networks carrying digital video conferencing, or the like), this paradigm provides sufficient availability. However, certain applications (e.g., voice circuits used in telephony) are extremely sensitive to even relatively short breaks in service. This is due to the limits for acceptable downtimes mandated by certain of the applicable industry standards.
For example, the synchronous optical network (SONET) protocol is widely employed in voice and data communications networks. SONET is a physical transmission vehicle capable of transmission speeds in the multi-gigabit range. In the case of voice communications carried over a SONET network, the failure of a link or node can disrupt a large number of voice circuits. Moreover, for most telephony implementations, failures must be detected within about 10 ms and restoration must occur within about 50 ms (per Bellcore's recommendations in GR-253 (GR-253: Synchronous Optical Network (SONET) Transport Systems, Common Generic Criteria, Issue 2 [Bellcore, December 1995], included herein by reference, in its entirety and for all purposes)). The short restoration time is critical in supporting applications, such as current telephone networks, that are sensitive to quality of service (QoS) because such detection and restoration times prevent old digital terminals and switches from generating alarms (e.g., initiating Carrier Group Alarms (CGAs)). Such alarms are undesirable because they usually result in dropped calls, causing users down time and aggravation. Restoration times exceeding 10 seconds can lead to timeouts at higher protocol layers, while those that exceed 1 minute can lead to disastrous results for the entire network.
As can be seen, a network element in such environments must be able to quickly detect and address failures such as those discussed above. Systems capable of providing such functionality tend to be large and quite complex. Such systems typically contain a number of subsystems, both hardware and software. Such subsystems are tasked with providing a variety of functions in support of the communications system's administrative, communication and other features. Thus, the management of such communications systems, while obviously necessary, can prove challenging.